Various circuits have been devised for detecting waveshapes by characteristics such as amplitude and the occurrence of a "peak" or "valley" of the wave. One problem frequently encountered with waveshape detectors is the tendency for them to falsely respond to noise signals which often accompany the incoming electrical wave. Another problem is the difficulty in designing a detector suitable for both low-frequency (long time period) and high-frequency (short time period) waves. These problems are particularly severe when high reliability is desired, such as in the case of nuclear explosion detectors which detect any incoming waves (optical radiation, for example) having the characteristic waveshape produced by a nuclear detonation. It is important that such detectors reliably indicate the occurrence of any nuclear explosion so that precautions can be taken against the danger of nuclear fall-out. It is also important that such detectors be immune to giving false responses to other kinds of electrical or optical waves, as this would cause unnecessary activity, and perhaps public panic and lack of confidence in the detection equipment. Furthermore, such detectors for nuclear explosion waves must be capable of detecting a wide range of waves having a "main peak" occurring in a time range from about 33 milliseconds to 10 seconds after the "first peak," as determined by the magnitude of the explosion.